The letter that future Nobel Prize winner Francis Crick wrote to his son Michael in 1953 about the structure of DNA has been sold at auction for $6 million, about half of which will go to the Salk Institute for Biological Studies in La Jolla, where Crick spent much of his career.

Michael Crick was only 12 when he received the letter, which included the first hand drawing of the double helix structure of DNA. Crick, James Watson and Maurice Wilkins won the 1962 Nobel in physiology of medicine for their discovery, which is regarded among the greatest scientific achievements of the 20th century.

The letter remained in the Crick family until April 10th, when it was sold with other items by Christie's auction house. The name of the person who bought the letter has not been disclosed, but Michael Crick formally announced that half of the proceeds will go to the Salk, where his father was on the faculty for almost 30 years.

In a statement, Salk President William Brody said, "The Salk Institute is enormously grateful for having had the privilege to know and work with Francis, and that Michael has chosen to honor his father's memory this way."

The gift is a timely one for the Salk. The institute is in the midst of its first major private fundraising campaign.